Because lithium-ion batteries have the advantages of high energy, high density, long storage life, and small size, the lithium-ion battery modules have been widely used in the fields of electric vehicles and energy storage. Because sustainability of the electric vehicle is not very high in general, a large number of lithium-ion batteries need to be connected in series or in parallel to improve the sustainability of the battery module.
At present, large-capacity rectangular batteries are only experimental products, that is because the rectangular battery has a large volume, it is difficult to ensure the safety performance after the rectangular batteries are assembled to form a module, and cost of the rectangular battery module and cost of the mono-rectangular battery are high. In contrast, steel-shell cylindrical lithium-ion batteries are more mature in technology, but the steel-shell cylindrical lithium-ion battery has low energy density, and when a plurality of mono-batteries are connected in series, once one battery fails, it is possible to cause serious safety problem with the whole battery module.